Telephone system



Aug. 17, 1937. WOLF TELEPHONE SYSTEM 2 Sheets-Sheet 1 Filed Aug. 25, 1936 3%: NED

INVENTOR. ZFR/TZ WOLF ATTORNEY.

Aug. 17, 1937. F. WOLF TELEPHONE SYSTEM Filed Aug. 25, 1936 2 Sheets-Shqet- 2 Nd b vU N wE . INVENTOR.

FRITZ WOLF 3 W H! G ATTORNEY.

Patented Aug. 17, 1937 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Germany Application January 25, 1936, Serial No. 60,763 In Germany February 18, 1935 8 Claims.

The present invention relates to the control of the junction point and is characterized in that the control means of the junction point are influenced simultaneously with the establishment of the call route over connecting devices of the exchange in a manner which corresponds to the calling line. By effecting the switching over at the junction only when the call route over the connecting devices has been established the control devices at the switching over point can be constructed in a manner which is particularly favorable to the efficiencyof an arrangement of this sort in comparison with arrangements. in which the switching over operation at the junction takes place at some other time. It is moreover possible to dispense with special switching over relays at the junction point. Dispensing 25 with special switching means in this way has, in addition to the very great technical advantage that the number of contacts in the speaking lines is reduced to a minimum and switching means which might for example cause distortion of the impulses are rendered completely unnecessary.

The invention is illustrated in connection with so-called two-party connections in which two subscribers stations whose lines are brought together at a common switching point are con- 35 nected at the switching point (UStZ) over a common connecting line VL. The invention is, however, not limited to two-party line systems, it is equally possible for more than two subscribers lines to be associated at the switching-over point 40 (UStI) and furthermore, instead of subscribers stations, connecting lines, party lines or the like may be connected up.

In the drawings Fig. 1 shows a circuit arrangement of an embodiment of the invention, while.

45 Fig. 2 is a modification thereof.

In the drawings two subscribers stations TStl T5152 are shown, whose lines are brought to the switching-over point UStl and are connected to the common connecting line VL. This connect- 50 ing line leads by way of the switching-over point UStZ to the exchange connection in which one approach to an individual preselecting device is provided for each subscriber of the two-party line system. Although in the embodiments the 55 preselecting devices are represented by call finders the invention is not limited to these. It is moreover not necessary for both the subscribers stations to be connected to different groups of preselecting devices. It is possible to lead the I approach lines to the same group of call finders 5 so that the two approaches are connected to different contacts of the call finder. In the embodiments the general plan in respect of two call finders (AS! and A82) is represented. Interconnection between the two subscribers of the two-party line is not possible. The main construction of the arrangements shown in the two embodiments is the same. In Fig. 1, however, a special auxiliary relay is provided at the switch- I ing-over point USt2 which controls the switching over of the junction at this point, while in Fig. 2 the control of the junction is effected by a relay provided for the individual lines in the call finder.

The switching operations according to the arrangement in Fig. 1 will first be described.

When the subscriber at station TStI, for example, takes up: his receiver. the following circuit is established for relay R! in the call finder ASI; earth, winding I of relay RI, battery, contact iii, resistance Wil, contact 262, a-lead of the connecting line, winding I of relay U l, contact 3u2, subscribcrs station TStl, contact 4112, wind- 5 ing II of relay Ul, contact 5ul, and earth. On account of the resistance Wil in this circuit relay U! at the switching-over point UStI does not energize. Relay RI at the call finder is, however, energized and by closing its contacts 61! causes the call finder AS! to be started up over the start lead AN and contact 'ltl which is in the rest position. The testing circuit for relay TI of the call finder is prepared over contact 8H and 9H. When the call finder tests on the calling line relay Ti energizes and brings the call finder to rest in the known way: earth in the group selecter, cwiper of the call finder ASl, contact 815, winding 4 II of relay RI, contact 9T! 01- lfltl, winding II of relay Tl, battery, earth. At the same time as relay Tl energizes relay Cl is energized over contact I lc2 when the call finder tests on the calling line. Relay CI is locked energized over its contact Mel and the high resistance WiZ. The energizing of relay Cl eliects the switching-over of the connecting line VL on to the connecting path established through the call finder AS! since contact ltcl is now open and contact Me! is closed. Moreover the high resistance Wii in the a-lead of the speaking line is short-circuited by means of contact 550] so that the potential which is connected up in the group selector operates in full force on the relay III at the switching-over point UStI. Relay UI is accordingly energized: earth, battery, relay AI, winding I in the group selector, cit-wiper of the call finder ASI, resistance WiI, contact 202, a-lead of the connecting line, winding I of relay UI, contact 3212 of the subscribers station TStI contact Mp2, winding II of relay UI, contact Sui, earth. Relay UI energizes and. closes contact I Gul thus completing the loop to the group selector. Relay UI remains energized in this loop until the release of the connection.

Relay CI moreover serves to characterize the approach for subscriber TSt2 at the final selector as engaged by connecting earth potential over contact I'IcI. Relay CI holds up over resistance Wi2 until the release of the connection. Windings II of relay RI and TI are connected in parallel with relay CI so that the current then, flowing over the relay CI is no longer sufficient to maintain the latter relay energized. Relay CI releases and by switching over its contacts Hal, I3cl, I5c| and I'IcI returns the system to normal.

The corresponding switching operations occur if station TStZ initiates a call when the connecting line-VL is disengaged. If, however, the connecting line is already engaged on account of the call set up by station TStI, the station 'IStZ is completely disconnected from the connecting line by the opening of contacts IBM and IiluI so that no disturbance of the existing call can occur.

In the case of incoming calls ringing current is connected either to the a-lead or to the b-lead of the connecting line according to the setting of the final selector and the bell of the particular station desired is operated over one lead of the connecting line and earth. At the same time the corresponding relay (CI or C2) is energized over the c-lead and effects the switching over of the junction at the switching-over point USt2. The further switching operations at the switchingover point UStZ then correspond to the operations occurring in the case of an outgoing call.

The manner of operation of the arrangement as shown in Fig. 2 will now be described. If the subscriber for example at station TStI wishes to initiate a call he takes up his receiver and thereby closes a circuit for relay RI in the call finder ASI: earth, battery, winding I of relay RI, contact Itl, 2t2, a-lead of the connecting line VL, winding I of relay UI, contact 3102, subscribers station TStI, contact 421.2, winding I of relay UI, contact Sui and earth. Relay UI does not energize since it is in series with the high resistance winding of relay RI in the call finder. On the other hand relay RI is energized and closes its contacts. Over contact 61'! the starting impulse is given over the start lead AN to the call finder in the known way. At the same time the testing circuit for relay TI in the call finder is prepared over contacts HI and 811. When the call finder tests on the calling line, relay TI energizes and brings the call finder to rest in the known mannor, earth in the group selector, c-wiper of the call finder, contact 'IrI, Winding II of relay RI, contact Stl winding II of relay TI, battery, earth. Relay TI energizes and first by closing contact I IltI causes the connecting line VL to be switched through to the call finder ASI and further over contact IItI efiects the connection of blocking potential to the c-lead of the final selector connection for subscriber T8152, and also disconnects the high resistance winding I of relay RI from the a-lead of the speaking line by opening contact ItI and closing contact IZtI. Relay RI holds up, however, over its winding II which occurs in the circuit of relay TI until the end of the call.

When the call finder has tested on the calling,

line the potential in the group selector which has been reached is connected to the two speaking leads of the connecting path set up over the call finder ASI. Accordingly a circuit is set up for relay UI at the switching-over point UStI and in this circuit the relay energizes: earth, battery, windingI of relay AI in the group selector, call finder ASI, contact 2t2, a-lead of the connecting line, winding I of relay UI, contact 3M2, subscribers station TStI, contact 4u2, winding II of relay UI, contact 511A, and earth. By closing contact I 2uI relay UI effects the switching through to the b-lead of the connecting line. Relay UI thus holds up in the loop to the group selector. The further setting up of the call takes place as for an individual subscribers call. On release of the connection relays TI and RI deenergize so that the switching devices both at the switching over points UStI and UStZ are returned to the rest position.

Corresponding switching operations take place when a call is initiated from subscribers station T5152. If however, station TStI is already engaged in a call and station TStZ then wishes to set up a callthis is prevented since after the energizing of relay UI contacts I3ul and l4u| are opened so that station TSt2 is completely disconnected from the connecting line. If, however, subscriber TStZ is engaged in a call relay selector characterized as being engaged on account of the earth potential c-lead over contact I5t2.

What is claimed is:

connected to the 1. In a telephone system, a common connecting line, telephone lines branched from one end of [1,

said common line and normally connected thereto, connecting paths branched from the other end of said common line, a switch in each of said connecting paths, controlling means at the junction of said common line and said connecting paths,

means responsive to a call from either one of said telephone lines for taking said common line into use and for extending the call over one of said connecting paths to the switch in said path,

means for operating the switch of either path to v.3

extend the call depending upon the line calling, and means responsive to the extension of the call by a switch for operating said junction controlling means.

2. In a telephone system, a common connecting line, telephone lines branched from one end of said common line and permanently connected thereto, connecting paths branched from the other end of said common line, a switch in each of said connecting paths each for extending calls a.

from said common line, controlling means at the junction of said connecting paths and said common line, means responsive to a call from one of said telephone'lines for'operating one of said switches to connect with the associated connect ing path and extend the call, said controlling means operated simultaneously with the exten sion of the call from a line to connect the calling telephone line with the connecting path and its associated switch.

3. In a telephone system as claimed in claim 2 in which the connecting switch has access to further switches for extending the call, means for testing said further switch for its busy or idle condition, and means in the event the further switch is idle and the call is extended for operating the junction controlling means.

4. In a telephone system, a common connecting line, telephone lines extending from one end of said common line, connecting paths extending from the other end of said common line, a switch in each connecting path for selecting the same,

a further switch connected to said first switch for extending the connection, switching means at the junction of said common line and said connecting paths, means responsive to a call from one of said telephone lines for initiating the operation of one of said switches to engage with the connecting path of the calling line, means for testing the busy or idle condition of said other switch after said first switch is operated, and means responsive to the extension of the connect ing path through said first switch for operating the junction switching means.

5. In a telephone system as claimed in claim 4 in which the switching means disconnects the other connecting paths and associated switches from the common line.

6. In a telephone system, a common connecting line, a pair of telephone lines branched from one end of said common line, a pair of connecting paths branched from the other end of said common line, a switch having access to the individual connecting paths, means responsive to a call from one of said telephone lines for initiating the operation of the switch over a path including one side of said common line and one side of the connecting path, the other of said telephones exercising its call initiation over the other side of the common line and one side of the other connecting path to the other switch, switching means for switching both sides of the common line through to one or the other of said connecting paths, said switch means operated to disconnect the other connecting path responsive to the switching through of the calling connecting path to the switch.

7. In a telephone system as claimed in claim 6 in which the switch comprises a finder switch that searches for the calling connecting path and upon engaging the connecting path tests for an outgoing trunk to extend the call and responsive to the extension of the call through the switch operates the junction switching means to disconnect the other connecting path.

8. In a telephone system as claimed in claim 6 in which after the connecting path is disconnected from the common line by the switching means the disconnected connecting path is guarded from seizure on incoming calls directed to the other telephone line.

FRITZ WOLF. 

